Gentoo Linux is a source-based Linux distribution created by Daniel Robbins. It uses Portage as official package management system which original design was based on FreeBSD's ports. The main portage's utility is called Emerge that is written in Python and can be used to install/uninstall packages.
Make.conf is Portage main configuration's file, because it contains many variables. For example, the best known : CFLAGS,CHOST,CXXFLAGS,USE, INPUT_DEVICES, VIDEO_CARDS,LINGUAS,GENTOO_MIRRORS.There are also many optional's variables like PORTDIR_OVERLAY. In this Linux distribution, the user compiles the source code locally according to their chosen configuration in order to improve their system and also to learn more about Linux.